Radius end mills can provide high efficiency in cutting and are commonly used. For example, PTL 1 discloses a radius end mill which includes a main gash formed at the front end which intersects with an end cutting edge of a chip removal flute and an auxiliary gash face formed in an outside area which intersects from the interface of the end cutting edge of the main gash face and the corner R cutting edge to the outer peripheral cutting edge. Further, PTL 2 discloses a radius end mill which includes a gash extending from an end cutting edge to a corner R edge.